1. Clearly expressed; easily understood: a lucid analysis of the problem.
2. Thinking or expressing oneself clearly, especially between periods of confusion; clearheaded: The feverish patient was lucid now and then.
3. Brightly lit; luminous: "A lucid yellow moon was rising when Luke wheeled his truck to the curb and got out" (Willie Morris).
4. Clear; transparent: a lucid stream.
[Latin lūcidus, from lūcēre, to shine; see leuk- in the Appendix of Indo-European roots.]
lu·cidi·ty, lucid·ness n.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendicies
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.